why does your body temperature increase during exercise

Temperature During Exercise You sweat more after you finish exercising than you do while you exercise. More than 70 percent of the energy that powers your muscles is lost as heat, causing your body temperature to rise during exercise. To keep your body temperature from rising too high, your heart pumps the heat in your blood from your muscles to your skin, you sweat and it evaporates to cools your body. Sweating is controlled by the temperature of the blood flowing to the part of the brain called the hypothalamus. When your temperature rises, you sweat more. During exercise, your heart beats very rapidly to pump blood to bring oxygen to your muscles and hot blood from the muscles to the skin where the heat can be dissipated. When you stop exercising, your heart immediately slows down, decreasing the amount of blood pumped to your skin, so your temperature rises higher and you sweat more.
LIVESTRONG. COM Why Does Body Temperature Increase During Exercise?

Why Does Body Temperature Increase During Exercise? Last Updated: Apr 24, 2015 A young woman is sweating during her workout and is standing with her hands on her head. Vigorous exercise boosts your body's heat production and can increase your body temperature by several degrees. Your working muscles are responsible for the increase in heat production, but your body's ability to retain or dissipate heat and your external environment also play a role in how high your core temperature rises during your workout. To work, your muscles need energy, which they obtain by burning fuels such as fats and carbohydrates in a series of chemical reactions that produce heat. As your muscles warm up during your workout, blood circulating through the muscles is also warmed, producing a rise in core temperature.

The amount of heat your muscles produce is related to the amount of work they perform. The more strenuous your workout, the more heat they produce. During very vigorous workouts, muscle heat production can increase 15 to 20 times above resting levels. How high your temperature rises during your workout depends not only on how much heat your muscles produce, but also on how fast your body loses heat. In cold conditions, your body loses heat rapidly. In hot, humid weather, your body is less able to dissipate excess heat, making overheating more of a risk. A rise in core temperature to above 104 degrees Fahrenheit can result in life-threatening heat stroke, so your body has a number of mechanisms to keep your core temperature within fairly narrow limits, even during a strenuous workout. As your core temperature increases during your workout, blood is shunted away from your core to your skin, which allows your skin to radiate more heat, reducing your temperature.

Sweating also helps to cool you. As sweat evaporates, it carries off excess heat. Because less sweat evaporates when the humidity is high, you're more likely to overheat in muggy weather than in dry conditions. As you become more fit with training, your body's ability to dissipate heat improves, a process called acclimatization. You begin sweating earlier in your workout, and at a lower temperature. If your core temperature rises above 104 degrees Fahrenheit, you're at risk for heat stroke, a potentially fatal condition that damages multiple body systems. To prevent the risk of heat-related illness during exercise, the American College of Sports Medicine recommends avoiding strenuous exercise during hot, humid weather, wearing light clothing and avoiding dehydration by drinking sufficient fluids before and during your workout.

Dehydration greatly adds to the risk of heat-related illness. Exercise Physiology for Health, Fitness and Performance; Sharon A. Plowman and Denise L. Smith Exercise Physiology: Energy, Nutrition and Human Performance; William D. McArdle et al. The hypothalamus is the part of the brain charged with monitoring and managing core body temperature. If your body temperature increases, the hypothalamus responds by attempting to cool you down. One of the most efficient ways to disperse heat is through evaporation. To do this, your body kicks off a sweat response by dilating blood vessels and warming the surface of your skin. This is why remaining hydrated is so important during intense exercise, especially if you're working out in hot weather.